Continuously variable transmission (CVT) are variously known in the form of belt drive transmission or in the form of toroidal drives. The Applicant's DE 198 44 374.9 thus describes a belt drive transmission which has a first cone pulley pair upon a drive shaft and a second cone pulley pair upon an output shaft, each cone pulley pair consisting of a first pulley stationary in axial direction and a second cone pulley movable in axial direction (respectively primary pulleys and secondary pulley). Between the cone pulley pairs extends a belt drive organ such as a pushing linked band. The primary and secondary pulleys are adjusted by a pressure medium with the aid of an electronic control device which via electromagnetic actuators and hydraulic valves controls the pressure level of the adjusting spaces of primary pulley and secondary pulley.
The toroidal drive has been described, for example, in the Applicant's WO 99/05433. It has input and output pulleys arranged in pairs and situated coaxially to a common shaft with their inner faces toroidally configured, the same as friction wheels placed between the pairs of input and output pulleys. The friction wheels are in frictional contact both with the input pulleys and with the output pulleys and transmit by frictional-engagement contact the torque transmitted to them by the input pulley to the output pulley, the rotational speed of the friction wheels being higher the greater the distance between their point of contact with the input pulley and the axis of rotation. The rotational speed of the output pulley, on the other hand, is higher the closer the contact point between friction wheel and output pulley is to the axis of rotation. By tilting the friction wheel sit is accordingly possible continuously and arbitrarily to adjust the rotational speed of the output pulley. To this end, the axes of rotation of the friction wheels are supported on a carrier which can be controlled via a swiveling device. Both input pulleys of both transmission assemblies are here non-turnably connected with a torque shaft while both output pulleys of both transmission assemblies, which are disposed in the transmission with reciprocal mirror symmetry and side by side, are arranged upon a common bushing turnably supported upon the torque shaft. The torque shaft is penetrated by an input shaft which is connected with a starting element of a motor vehicle such as a torque converter or a wet-running starting clutch of the prime mover of the vehicle.
The problem on which this invention is based is to reduce the installation space needed for this transmission assembly and to simplify the oil supplies.